In recent years, high-performance display devices such as a large screen television have become widely used. Some of the display devices include a light source for applying light in addition to a display panel. The light source is used to provide a display on the display panel. In such devices, an image quality is highly affected by uneven luminance that is caused in a displayed image by the light source and uneven color that is caused by properties of the display panel (hereinafter, the uneven luminance and the uneven color may be collectively referred to as “display unevenness”), and thus correction of the display unevenness is required.
For example, an optical sheet is used to reduce the uneven luminance. The optical sheet is configured to diffuse the light passing therethrough, and thus the uneven luminance is reduced by such properties. Further, as a technology for reducing the uneven color, a technology for correcting an image signal input to a pixel of the display device is known (for example, Patent Document 1). The correction of the image signal changes color that is provided by the pixel, and thus the uneven color can be reduced.